Press felts are used within the press section of paper machines and the like to transport the fiber web through the press section and, correspondingly, to receive water removed from the fibre web in the press, whereby water is removed from the felt separately. The use of prior art press felt structures causes rewetting problems because water cannot be removed from the felt until after the nip when the felt has been separated from the web. This is due to, e.g., the following reasons. When being pressed, the web and the felt are compressed, so that water contained in the web enters the felt, and thereby the water contained in the web and the water contained in the felt are in close contact. When the web and the felt return to their original dimensions after the nip, the capillary force caused by the structure of the web and the felt is considerably greater in the web than in the felt. As a result, the water remaining in the web is able to suck water from the felt through its surface layer so that the obtained water removal result is deteriorated considerably.
In prior art press felts, in an attempt to eliminate the effect of this phenomenon, the surface layer of the felt on the side of the web has been made as compact as possible in order to increase its capillary force to that the water would be sucked into the felt instead of being sucked into the web. However, no greater improvement in the rewetting problem has been obtained in this way.